It is known to strategically locate electronic devices throughout an automotive vehicle. Each device is dedicated to at least one operation, such as a control or diagnostic operation. It may be necessary in the carrying out of the various operations for the devices to share data, such as data indicating vehicle parameter values, which must be frequently exchanged between various devices while the vehicle is operating. A single, global, bi-directional serial communication link has been used for data exchange between various electronic devices on-board a vehicle. Each of the devices has read and write access to the link.
The integrity of the link may thus depend on the integrity of any of the devices that access the link. For example, certain short-circuit fault conditions in any device accessing the link have potential to pollute the link and thus affect the performance of the other devices accessing the link, such as by interfering with the sharing of important vehicle parameter data between the devices. Indeed, the performance and reliability of a fault-free communication link and a number of fault-free devices using the link could be reduced through a fault condition in just one device on the link.
Sophisticated communications control and diagnostics for a number of devices sharing a communication link is known. Local Area Networks LANs are well-known in the communication art and typically include fault protections that attempt to isolate device faults so as to minimize the impact of such faults on the operation of the link or of other devices relying thereon. The fault protections provided by LANS are not appropriate for automotive on-board communications for several reasons. The sophisticated protections of LANs consume a prohibitive amount of power and physical space for application on-board conventional vehicles in which power and space are limited. The cost of such sophisticated protections are likewise prohibitive. For example, complex electronics or even dedicated controllers may, at significant expense, be used in conventional LAN technology to provide fault protection. To make these electronics compatible with the relatively harsh operating environment on-board an automotive vehicle would likely add further expense. Finally, the intrusiveness of the typical LAN fault protection circuitry in the communication it is designed to protect make it undesirable for application on-board a vehicle. For example, a substantial amount of information in the form of serial data on the communication link may be lost while the LAN fault protection circuitry is providing a remedy for a detected fault. While this loss of information may be tolerable in other applications, it is not tolerable in a moving automotive vehicle.
It would therefore be desirable to provide for detection and isolation of faults in a communication network on-board an automotive vehicle without adding significant expense, package size, or power consumption, and without interfering significantly with communications on the network.